As far as I know a subscription model will be introduced with Version 4.x.x.x of Locus, But Locus 4.x.x.x is not released yet.
So for now for Locus Pro 3.x.x.x you have only pay once the price, thats it. No more costs for Locus Pro 3.x.x.x . And you can install Locus Pro 3.x.x.x on any device using the same google account you bought Locus Pro 3.x.x.x (see here)
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